Four American Museum of Natural History paleontologists have overturned a 1950s claim that a theropod dinosaur called Coelophysis was a cannibal that ate juveniles of its own kind, forcing a revision of a popular story of dinosaur behavior that has been repeated many times in the scientific literature, popular media, and museum exhibits. In order to test the well-known cannibal-Coelophysis hypothesis, the team re-examined the anatomy of the two celebrated Coelophysis fossils said to exhibit cannibalism, as well as the structure of the bone found in the abdominal cavity of one of the specimens.

Share This

Four American Museum of Natural History paleontologists have overturned a 1950s claim that a theropod dinosaur called Coelophysis was a cannibal that ate juveniles of its own kind, forcing a revision of a popular story of dinosaur behavior that has been repeated many times in the scientific literature, popular media, and museum exhibits.

Related Articles

In order to test the well-known cannibal-Coelophysis hypothesis, the team re-examined the anatomy of the two celebrated Coelophysis fossils said to exhibit cannibalism, as well as the structure of the bone found in the abdominal cavity of one of the specimens (the complete specimens are on permanent display in the Museum's Hall of Saurischian Dinosaurs).

In one specimen, the Museum scientists found that the carnivorous dinosaur's last meal was a primitive crocodile, not a dinosaur of any kind, let alone a Coelophysis; in the second specimen, the new analysis shows that the remains identified as a last meal actually are located outside the larger animal's ribcage and are possibly too large to have been eaten whole.

The adult dinosaur's skeleton probably was crushed on top of juvenile remains, creating the illusion that the remains were inside the gut of the adult dinosaur. And the Museum team found that the "gut content" bones actually are too shapeless to be identified as belonging to any dinosaur, or specifically a Coelophysis. They can only be identified as belonging to a sauropsid, a group of vertebrate animals that includes all modern and most extinct reptiles, including non-avian dinosaurs, pterosaurs, plesiosaurs, and others.

Overall, the anatomical findings, and a review by the researchers of remaining claims of cannibalism in theropod dinosaurs, fail to support the claim that Coelophysis was a cannibal and suggest that cannibalism in non-avian theropod dinosaurs in general was much more rare than previously thought. Agalychnis calcarifer Sterling Nesbitt inspecting the Coelophysis slab Credit: Mick Ellison, AMNH

The new research is described in the peer-reviewed journal Biology Letters by Sterling J. Nesbitt and Alan H. Turner, graduate students enrolled at Columbia University who study in the American Museum of Natural History's Division of Paleontology; Gregory M. Erickson, Assistant Professor of Anatomy and Vertebrate Paleobiology at Florida State University and a Research Associate at the Museum; and Mark A. Norell, Curator in the Museum's Division of Paleontology.

"Our research shows that the evidence for cannibalism in Coelophysis is non-existent, and the evidence for cannibalism in other theropod dinosaurs is quite thin. These findings offer new insight into the behavior of some of the earliest dinosaurs," Mr. Nesbitt said. "We hope to examine additional theropod fossils found at the location where these fossils were found to learn more about their prey choices."

The two specimens were unearthed in 1947 by crews from the Museum as part of an enormous bed of hundreds of skeletons of the early theropod Coelophysis bauri from the Upper Triassic (210 million years old) found near Ghost Ranch in north-central New Mexico. Soon thereafter, the two Coelophysis specimens that are the focus on this new research were prepared as a single fossil slab and revealed groups of small reptile bones that appeared to lie within the dinosaurs' body cavities.

The late Edwin H. Colbert, Curator of Fossil Reptiles and Chairman of the Department of Vertebrate Paleontology at the Museum from 1930 to 1970, asserted that the remains represented juveniles of Coelophysis and presented this as evidence of dinosaur cannibalism, generating the finding that was repeated over the years. [Dr. Colbert died in 2001, ending a rich academic career of more than 70 years that helped popularize the study of dinosaurs.]

"Cannibalism is seen among carnivorous animals today, but isn't common in living dinosaurs--birds. The behavior is really only prevalent among colonial sea birds and birds of prey," Mr. Turner said. "This made us wonder just how widespread cannibalism was among non-avian dinosaurs, and the case for Coelophysis was the strongest."

These questions led the Museum team to test the cannibal-Coelophysis hypothesis and conduct the anatomical analysis that overturned the claim of cannibalism. Along with the anatomical work, the research involved taking thin histological sections from the juvenile femur, or thigh bone, found in the gut of one of the specimens and comparing them with thin sections from the femurs of another Coelophysis specimen and from an early crocodile relative (crocodylomorph). The samples were used to determine how the animals' bones grew, and the results showed that the bone from the Coelophysis's gut grew like the crocodylomorph bone grew, not like the dinosaur bone grew, confirming the anatomical conclusion that this Coelophysis specimen was not a cannibal.

While there is evidence to suggest that cannibalism exists among theropod dinosaurs, the team re-examined the few other cases of "cannibalism" in Coelophysis and found that they were based on indirect evidence, such as digested material and intestinal casts, that reveals too little detail to support a claim of cannibalism. Similarly, claims for cannibalism in other theropods are based in part on tyrannosaur bite marks on the remains of tyrannosaurs from the Dinosaur Park Formation of Alberta but there are at least two species of tyrannosaurs in this location, so it cannot be concluded definitively that these tyrannosaurs ate their own. One piece of evidence for cannibalism in theropods remains--bite marks and teeth associated with Majungatholus atopus.

"In order for paleontology to continue to advance at the rapid pace that it has in the past two decades, it is important that paleontologists at the Museum and beyond continue to test hypotheses and assumptions made about dinosaur diversity and biology, including those about cannibalism," Dr. Norell said. "Our recent work, including this latest research on prey choice among theropod dinosaurs, reaches across many disciplines involving paleontologists, biomechanical engineers, physiologists, and others, and is revolutionizing our understanding of the mysterious lives of dinosaurs."

The work on the Coelophysis specimens was funded by the National Science Foundation and the American Museum of Natural History. The thin section (histological) analyses also were supported by the National Science Foundation.

More Fossils & Ruins News

Featured Research

Mar. 31, 2015  Scientists have uncovered the earliest fossilized evidence of an insect caring for its young. The findings push back the earliest direct evidence of insect brood care by more than 50 million years, ... full story

Mar. 31, 2015  Paleontologists have discovered two new species of Saurichthys. The ~242 million year old predatory fishes were found in the fossil Lagerstไtte Monte San Giorgio, in Ticino. They are distinct from ... full story

Mar. 31, 2015  In the 1990s the discovery of the oldest human made and completely preserved wooden hunting weapons made the Paleolithic excavation site in Schoningen internationally renowned. Contained within the ... full story

Mar. 30, 2015  A new study reports that marine ecosystems can take thousands, rather than hundreds, of years to recover from climate-related upheavals. The study's authors analyzed thousands of invertebrate fossils ... full story

Mar. 27, 2015  What do butterflies, spiders and lobsters have in common? They are all surviving relatives of a newly identified species called Yawunik kootenayi, a marine creature with two pairs of eyes and ... full story

Mar. 27, 2015  Scientists have produced a 3-D reconstruction of the remains of a two-year-old Neanderthal recovered from an excavation carried out back in the 1970s at La Ferrassie (Dordogne, France). The work ... full story

Mar. 26, 2015  New research harnessing fragmentary fossils suggests our genus has come in different shapes and sizes since its origins over two million years ago, and adds weight to the idea that humans began to ... full story

Mar. 25, 2015  New findings from an international team of archaeological researchers highlight the complexity of geopolitics in Aztec era Mesoamerica and illustrate how the relationships among ancient states ... full story

Mar. 24, 2015  A previously undiscovered species of crocodile-like amphibian that lived during the rise of dinosaurs was among Earth's top predators more than 200 million years ago, a study shows. Palaeontologists ... full story

Featured Videos

Ancient Egyptian Beer Making Vessels Discovered in Israel

AFP (Mar. 30, 2015)  Fragments of pottery used by Egyptians to make beer and dating back 5,000 years have been discovered on a building site in Tel Aviv, the Israeli Antiquities Authority said on Sunday. Duration: 00:51
Video provided by AFP

Jan. 7, 2014  Dinosaur fossils are exceptionally rare in the Arabian Peninsula. Scientists have now uncovered the first record of dinosaurs from Saudi Arabia. What is now dry desert was once a beach littered with ... full story

Feb. 28, 2013  A paleontologist and his team have discovered a new species of herbivorous dinosaur and published the first fossil evidence of prehistoric crocodyliforms feeding on small ... full story

Dec. 6, 2011  A new species of horned dinosaur was just announced by an international team of scientists, nearly 100 years after the initial discovery of the fossil. The animal, named Spinops sternbergorum, lived ... full story

Oct. 15, 2010  It turns out that the undisputed king of the dinosaurs, Tyrannosaurus rex, didn't just eat other dinosaurs but also each other. Paleontologists from the United States and Canada have found bite ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.